A Critique of New Water Quality Criteria in Georgia: Policy and Ecological Implications

Proceedings of the 1999 Georgia Water Resources Conference, March 30 and 31, Athens, Georgia.The objective of the paper is to examine recent changes in the Georgia Rules for Water Quality Control. The State of Georgia changed surface water metals criteria from a total recoverable standard to a dissolved standard These· standards were changed to reflect the biologically available fraction of metals in surface waters. These changes have far reaching effects on NPDES permits, TMDL calculations, and sediment contamination and may have negative impacts on Georgia surface waters.Sponsored and Organized by: U.S. Geological Survey, Georgia Department of Natural Resources, The University of Georgia, Georgia State University, Georgia Institute of TechnologyThis book was published by the Institute of Ecology, The University of Georgia, Athens, Georgia 30602-2202 with partial funding provided by the U.S. Department of Interior, geological Survey, through the Georgia Water Research Insttitute as authorized by the Water Research Institutes Authorization Act of 1990 (P.L. 101-397). The views and statements advanced in this publication are solely those of the authors and do not represent official views or policies of the University of Georgia or the U.S. Geological Survey or the conference sponsors

Towards More Realistic Estimates of DOM Decay in Streams: Incubation Methods, Light, and Non-Additive Effects

Dissolved organic matter (DOM) is the largest pool of organic matter in aquatic ecosystems and is a primary substrate for microbial respiration in streams. However, understanding the controls on DOM processing by microbes remains limited, and DOM decay rates remain largely unconstrained. Many DOM decay rates are quantified with bioassays in dark bottles, which may underestimate DOM decay in streams because these bioassays do not include a benthic zone and do not account for abiotic factors of DOM loss, such as photodegradation and volatilization. We measured decay of labile and semi-labile DOM over 3 d in experimental streams and bottle bioassays. Incubations included 3 types of labile DOM (algal, light-degraded soil, and light-degraded plant leachates) and 2 types of semi-labile DOM (plant and soil leachates). We also quantified decay rates when labile and semi-labile DOM were mixed to test for non-additive effects, or priming, of semi-labile DOM by labile DOM. We converted dissolved organic carbon (DOC) decay rates to half-lives and uptake velocities and compared these metrics to previous studies that quantified DOC loss in bioassays or real streams. Percent DOC lost over time, or biodegradable DOC, was greater in experimental streams than in bioassays. DOC decay rates and uptake velocities did not differ between bioassays and experimental streams but were lower than in real streams. Mixing of labile and semi-labile DOM resulted in both positive and negative non-additive effects. Consistent non-additive effects were difficult to quantify because decay rates were not constant over the course of each incubation, as shown by faster decay rates calculated over the first 6 h of incubation compared to \u3e70 h. Decay rates of leachates from natural substrates (e.g., algae and soil) incubated over short periods of time (hours–days) are needed for models that aim to quantify organic matter transformation in aquatic ecosystems with short residence times, such as rivers and streams

A Framework for Establishing Restoration Goals for Contaminated Ecosystems

This article represents 1 of 6 articles in the special series “Restoration of Impaired Ecosystems: An Ounce of Prevention or a Pound of Cure?” The articles result from a Technical Workshop organized by SETAC and the Society for Ecological Restoration, held June 2014 in Jackson, Wyoming, that focused on advancing the practice of restoring ecosystems that have been contaminated or impaired from industrial activities.As natural resources become increasingly limited, the value of restoring contaminated sites, both terrestrial and aquatic, becomes increasingly apparent. Traditionally, goals for remediation have been set before any consideration of goals for ecological restoration. The goals for remediation have focused on removing or limiting contamination whereas restoration goals have targeted the ultimate end use. Here, we present a framework for developing a comprehensive set of achievable goals for ecological restoration of contaminated sites to be used in concert with determining goals for remediation. This framework was developed during a Society of Environmental Toxicology and Chemistry (SETAC) and Society of Ecological Restoration (SER) cosponsored workshop that brought together experts from multiple countries. Although most members were from North America, this framework is designed for use internationally. We discuss the integration of establishing goals for both contaminant remediation and overall restoration, and the need to include both the restoration of ecological and socio-cultural-economic value in the context of contaminated sites. Although recognizing that in some countries there may be regulatory issues associated with contaminants and clean up, landscape setting and social drivers can inform the restoration goals. We provide a decision tree support tool to guide the establishment of restoration goals for contaminated ecosystems. The overall intent of this decision tree is to provide a framework for goal setting and to identify outcomes achievable given the contamination present at a site. Integr Environ Assess Manag 2016;12:264–272. 2015 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC

Long‐term research reveals multiple relationships between the abundance and impacts of a non‐native species

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147876/1/lno11029.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147876/2/lno11029_am.pd

Metabolism, Gas Exchange, and Carbon Spiraling in Rivers

Ecosystem metabolism, that is, gross primary productivity (GPP) and ecosystem respiration (ER), controls organic carbon (OC) cycling in stream and river networks and is expected to vary predictably with network position. However, estimates of metabolism in small streams outnumber those from rivers such that there are limited empirical data comparing metabolism across a range of stream and river sizes. We measured metabolism in 14 rivers (discharge range 14–84 m3 s−1) in the Western and Midwestern United States (US). We estimated GPP, ER, and gas exchange rates using a Lagrangian, 2-station oxygen model solved in a Bayesian framework. GPP ranged from 0.6–22 g O2 m−2 d−1 and ER tracked GPP, suggesting that autotrophic production supports much of riverine ER in summer. Net ecosystem production, the balance between GPP and ER was 0 or greater in 4 rivers showing autotrophy on that day. River velocity and slope predicted gas exchange estimates from these 14 rivers in agreement with empirical models. Carbon turnover lengths (that is, the distance traveled before OC is mineralized to CO2) ranged from 38 to 1190 km, with the longest turnover lengths in high-sediment, arid-land rivers. We also compared estimated turnover lengths with the relative length of the river segment between major tributaries or lakes; the mean ratio of carbon turnover length to river length was 1.6, demonstrating that rivers can mineralize much of the OC load along their length at baseflow. Carbon mineralization velocities ranged from 0.05 to 0.81 m d−1, and were not different than measurements from small streams. Given high GPP relative to ER, combined with generally short OC spiraling lengths, rivers can be highly reactive with regard to OC cycling. © 2015, Springer Science+Business Media New York

Scaling Dissolved Nutrient Removal in River Networks: A Comparative Modeling Investigation

Along the river network, water, sediment, and nutrients are transported, cycled, and altered by coupled hydrological and biogeochemical processes. Our current understanding of the rates and processes controlling the cycling and removal of dissolved inorganic nutrients in river networks is limited due to a lack of empirical measurements in large, (nonwadeable), rivers. The goal of this paper was to develop a coupled hydrological and biogeochemical process model to simulate nutrient uptake at the network scale during summer base flow conditions. The model was parameterized with literature values from headwater streams, and empirical measurements made in 15 rivers with varying hydrological, biological, and topographic characteristics, to simulate nutrient uptake at the network scale. We applied the coupled model to 15 catchments describing patterns in uptake for three different solutes to determine the role of rivers in network-scale nutrient cycling. Model simulation results, constrained by empirical data, suggested that rivers contributed proportionally more to nutrient removal than headwater streams given the fraction of their length represented in a network. In addition, variability of nutrient removal patterns among catchments was varied among solutes, and as expected, was influenced by nutrient concentration and discharge. Net ammonium uptake was not significantly correlated with any environmental descriptor. In contrast, net daily nitrate removal was linked to suspended chlorophyll a (an indicator of primary producers) and land use characteristics. Finally, suspended sediment characteristics and agricultural land use were correlated with net daily removal of soluble reactive phosphorus, likely reflecting abiotic sorption dynamics. Rivers are understudied relative to streams, and our model suggests that rivers can contribute more to network-scale nutrient removal than would be expected based upon their representative fraction of network channel length

Comparing streambed light availability and canopy cover in streams with old-growth versus early-mature riparian forests in western Oregon

Light availability strongly influences stream primary production, water temperatures and resource availability at the base of stream food webs. In headwater streams, light is regulated primarily by the riparian forest, but few studies have evaluated the influence of riparian forest stand age and associated structural differences on light availability. In this study, we evaluate canopy cover and streambed light exposure in four second-order streams with paired reaches of primary old-growth versus second-growth mature riparian forests. Stand age class is used as a proxy here for canopy complexity. We estimated stream canopy cover using a spherical densiometer. Local streambed light exposure was quantified and compared within and between reaches using fluorescein dye photodegradation. Reaches with complex old-growth riparian forests had frequent canopy gaps which lead to greater stream light availability compared to adjacent reaches with simpler second-growth riparian forests. We quantified light exposure at relatively high resolution (every 5m) and also found greater variability in stream light along the reaches with old-growth riparian forests in three of the four streams. Canopy gaps were particularly important in creating variable light within and between reaches. This work demonstrates the importance of the age, developmental stage, and structure of riparian forests in controlling stream light. The highly variable nature of light on the stream benthos also highlights the value of multiple measurements of light or canopy structure when quantifying stream light.Keywords: Riparian forest, sunfleck, stream light, Solar radiation, PAR, canopy ga

Recovery and resilience of urban stream metabolism following Superstorm Sandy and other floods

Urban streams are exposed to multiple different stressors on a regular basis, with increased hydrological flashiness representing a common urban stream stressor. Stream metabolism, the coupled ecosystem functions of gross primary production (GPP) and ecosystem respiration (ER), controls numerous other ecosystem functions and integrates multiple processes occurring within streams. We examined the effect of one large (Superstorm Sandy) and multiple small and moderately sized flood events in Baltimore, Maryland, to quantify the response and recovery of urban stream GPP and ER before and after floods of different magnitudes. We also compared GPP and ER before and after Superstorm Sandy to literature values. We found that both GPP and ER decreased dramatically immediately following floods of varying magnitudes, but on average GPP was more reduced than ER (80% and 66% average reduction in GPP and ER, respectively). Both GPP and ER recovered rapidly following floods within 4–18 d, and recovery intervals did not differ significantly between GPP and ER. During the two-week recovery following Superstorm Sandy, two urban streams exhibited a range of metabolic activity equivalent to ~15% of the entire range of GPP and ER reported in a recent meta-analysis of stream metabolism. Urban streams exhibit a substantial proportion of the natural variation in metabolism found across stream ecosystems over relatively short time scales. Not only does urbanization cause increased hydrological flashiness, it appears that metabolic activity in urban streams may be less resistant, but also more resilient to floods than in other streams draining undeveloped watersheds, which have been more studied. Our results show that antecedent conditions must be accounted for when drawing conclusions about stream metabolism measurements, and the rapid recovery and resilience of urban streams should be considered in watershed management and stream restoration strategies targeting ecosystem functions and services

Ancient encaustic: An experimental exploration of technology, ageing behaviour and approaches to analytical investigation

The composition of the ancient wax-based painting technique known as encaustic has long been the subject of debate. Ancient sources provide few details of the technology, and modern understanding of the medium is restricted to theoretical interpretation and experimental observation. In this multi-analytical collaborative study, a number of analytical approaches were used to investigate the physical and molecular properties of a range of experimentally prepared encaustic paints before and after ageing. Analysis using gas chromatography mass spectrometry, Fourier transform infrared spectroscopy (invasive and non-invasive), X-ray diffraction and thermogravimetric analysis demonstrated how differences in the technology of production alter the properties and composition of the medium and showed how these are modified by the addition of pigment and the effects of ageing. Comparison of results from the different analytical techniques highlights the benefit of an integrated analytical approach to the analysis of ancient encaustic paints and the fundamental importance of insights from invasive study to evaluating the results of non-invasive analysis

Effects of spatially heterogeneous lakeside development on nearshore biotic communities in a large, deep, oligotrophic lake

Sewage released from lakeside development can reshape ecological communities. Nearshore periphyton can rapidly assimilate sewage-associated nutrients, leading to increases of filamentous algal abundance, thus altering both food abundance and quality for grazers. In Lake Baikal, a large, ultra-oligotrophic, remote lake in Siberia, filamentous algal abundance has increased near lakeside developments, and localized sewage input is the suspected cause. These shifts are of particular interest in Lake Baikal, where endemic littoral biodiversity is high, lakeside settlements are mostly small, tourism is relatively high (~1.2 million visitors annually), and settlements are separated by large tracts of undisturbed shoreline, enabling investigation of heterogeneity and gradients of disturbance. We surveyed sites along 40 km of Baikal’s southwestern shore for sewage indicators—pharmaceuticals and personal care products (PPCPs) and microplastics—as well as periphyton and macroinvertebrate abundance and indicators of food web structure (stable isotopes and fatty acids). Summed PPCP concentrations were spatially related to lakeside development. As predicted, lakeside development was associated with more filamentous algae and lower abundance of sewagesensitive mollusks. Periphyton and macroinvertebrate stable isotopes and essential fatty acids suggested that food web structure otherwise remained similar across sites; yet, the invariance of amphipod fatty acid composition, relative to periphyton, suggested that grazers adjust behavior or metabolism to compensate for different periphyton assemblages. Our results demonstrate that even low levels of human disturbance can result in spatial heterogeneity of nearshore ecological responses, with potential for changing trophic interactions that propagate through the food web